Caption: Colour-enhanced Scanning Electron Micrograph (SEM) of Staphylococcus epidermidis, one of 33 known species belonging to the genus Staphylococcus. It is part of human skin flora (commensal). Although S. epidermidis is not usually pathogenic, patients with compromised immune systems are often at risk for developing an infection. These infections can be both nosocomial or community acquired, but they pose a greater threat to hospital patients. S. epidermidis is also a major concern for people with catheters or other surgical implants because it is known to cause biofilms that grow on these devices. This image shows an early stage of biofilm development. Image width: 16 micrometers. Magnification: 6250x if the image is printed 10 cm wide.